Self-defrosting windshield with automatically variable transparency

ABSTRACT

A windshield assembly includes two window panes with an elastic peripheral cushion therebetween defining a compartment through which a heated, tinted liquid is circulated under thermostat control. Hydraulically operated cylinders connected to one window pane moves it with respect to the other window pane under control of a photoresponsive device for changing the transparency of the liquid in the compartment.

1 51 Oct. 3, 1972 uulltu BIaIES ratent Dockery [541 SELF-DEFROSTINGWINDSHIELD 3,343,868 9/1967 Manookian..................296/97 WITHAUTOMATICALLY VARIABLE 1,903,917 4/1933 Dysart ....296/97 TRANSPARENCYFOREIGN PATENTS OR APPLICATIONS [72] Invent wane 778,128 2/1968 c6ma11a......................3s0/312 2,007,664 1/1970France.......,.................52/171 Drive, Tuscaloosa, Ala. 35401 Aug.21, 1970 [22] Filed:

Primary Examiner-Benjamin Hersh [21] Appl' 65,884 AssistantExaminer-Leslie J. Paperner Attorney-Polachek, Saulsbury & HoughABSTRACT A windshield assembly includes two window panes with an elasticperipheral cushion therebetween defining a compartment through which aheated, tinted liquid is circulated under thermostat control. Hydrau- 17 5 .l. nmnu %Bw JWZ 5 5 3 %;2 1 "W H m9m HY/ 2 "R 5 W F u .3 3 6 M 9% mu m m M "mm L m Cd S Ld U .mF M n1 0 m 5 55 [56] References Cited UNITEDSTATES PATENTS lically operated cylinders connected to one window panemoves it with respect to the other window pane under control of aphotoresponsive device for chang- 2,332,060 10/1943coneran......................52/171 th t fth th rt t 2,537,011 1/1950Aparicio....................350/l61 mg e ransparencyo e m ecompa2,386,339 10/1945 OConnor....................52/17l 4 Claims, 6 DrawingFigures PATENTEnum I972 3. 695.681

sum 1 or 2 IT $75 l H3 RESERVOIR PUMP L] 62 64 66 INVENTOR.

WALTER E. DOCKERY ATTURNEY5 MANUAL PATENTEII B I973 3.695.681

SHEET 2 or 2 FROM PUMP '2 5O 67 69 2 TO MASTER CYLINDER "0 I06 (D I I 39To BATTERY To IGNITION IGNITION TO MASTER CYLINDER 48 40 FROM PUMTDTSOTO HEATER RESERVOIR jig. 4.

I04 EB T To IGNITION MASTER CONTROL HEAT CONTROL MANUAL 'H CONTROLINVENTOR. WALTER E. DOCKERY WW ATTURNEYS SELF-DEFROSTING WINDSHIELD WITHAUTOMATICALLY VARIABLE TRANSPARENCY This invention relates to the art ofWindshields for automotive vehicles and more particularly concerns aheated, self-defrosting tinted windshield whose transparency isautomatically variable.

It has been proposed heretofore to "provide a windshield having a pairof relatively movable transparent panes enclosed in a peripheral framein such a way as to define a compartment into which a tinted liquid canbe passed to vary transparency of the windshield. This system has notbeen found practical because of a number of serious deficiencies. In thefirst place, it has not been found feasible to use the tinted liquid toforce the panes apart. Secondly, the prior systems required manualcontrol and did not effect change in transparency automatically.Thirdly, the prior systems lacked self-defrosting heating features.Other difficulties involved complexity, high cost and lack of generalversatility of the prior systems.

The present invention is directed at a windshield assembly whichovercomes the difficulties and disadvantages heretofore encountered andin addition affords advantages not attainable in prior Windshields.According to the invention there is provided a windshield assemblyhaving movably spaced inner and outer panes closed peripherally by aflexible frame. The inner pane is movable by a hydraulically controlledmechanical system. A tinted liquid which serves as a light filter iscirculated between the panes by a pump. The liquid may be heated toeffect melting of ice and snow on the outer pane and to dissipatecondensation of moisture on the inner pane. The movement of the innerpane is automatically controllable by a light responsive photoelectriccell to vary the quantity of tinted liquid between the pane for changingits transparency. A thermostat controls heating of the circulatingliquid. The assembly is arranged so that heating and transparencyvariation can be automatically or manually controlled, and each can beindependently activated or deactivated.

Other and further features, objects and advantages of the invention willbecome apparent from the following detailed description taken togetherwith the drawings, wherein:

FIG. 1 is a front view of a windshield assembly embodying the invention.

FIG. 2 is an enlarged vertical sectional view taken on line 2--2 of FIG.1.

FIG. 3 is an enlarged vertical sectional view with parts broken awaytaken on line 3-3 of FIG. 1.

FIG. 4 is a rear view of the windshield assembly.

FIG. 5 is a diagram of the control circuitry of the assembly.

FIG. 6 is a front view of the control panel of the assembly.

Referring first to FIGS. l-4, there is shown a windshield assembly 10for an automotive vehicle having a roof 12, cowl 14 and hood 16. Thewindshield assembly includes an outer or front window pane 18 mounted ina support which includes a resilient sealing gasket 20 and rectangularfront frame,22. A movable inner window pane 24 is disposed parallel toand behind pane 18. Interposed between the panes 18, 24 at theirperipheral margin is an elastic frame 26. The rear peripheral margin ofpane 24 is backed by an L-shaped frame 28. Frames 22 and 28 are rigidmembers. Bolts 30 integral with frame 22 extend rearward throughregistering holes in gasket 20, frame 26, pane 24 and frame 28. Thebolts terminate in threaded ends on which are cap nuts 32. Coil springs33 on the bolts bear against frame 28 and thus maintain a tight sealbetween the panes 18, 24 and frame 26. Frame 26 can be compressed toreduce the spacing between the panes and to lower the volume of liquid34 in compartment 36 defined between the panes and frame 26. Liquid 34is tinted green or other desired color and has such a low freezing pointthat for all practical purposes it may be considered non-freezing. Theliquid can be an aqueous solution of propylene glycol or otherantifreeze agent.

The inner pane is supported at its lower edge by bearing brackets 38attached to cowl 14. Brackets 38 have ball bearings 39 on which thelower wall 40 of frame 28 is slidable. Upper brackets 42 are attached toroof 12 and have ball bearings 44. The upper wall 46 of frame 28slidably contacts bearings 44. Two upper hydraulic cylinders 47 and twolower cylinders 48 are employed to move the pane 24. The extent oftravel of pane 24 is about one quarter of an inch or so toward and awayfrom outer pane 18. Each cylinder, 47 and 48 is supported by a bracket49 or 50 on roof 12 or cowl 14. Inside each cylinder is a piston 52having a piston rod 54 secured to the rear wall of frame 28. Hydraulicfluid 56 inside'the cylinder passes into and out of the cylinder via alateral conduit 58 connected via manifold 60 to master cylinder 62.Cylinder 62 is located under hood 16. The fluid can be forced intocylinders 47, 48 by a piston 64 in cylinder 62 actuated by plunger 66 ofa solenoid 65. By this arrangement the inner pane can be moved closer topane 24 while frame 26 is compressed. Relaxation of fluid pressure inthe cylinders permits expansion of the compressed elastic frame.Movement of pane 24 is under control of a photoelectric cell 67 mountedin a housing 69 at the top of frame 28.

Liquid 34 is circulated through compartment 36 by a pump 70. The pumpdraws the liquid from a tank or reservoir 72 and passes it via main line74 and branch lines 76' through openings in frame 28 and pane 24 to thetop of compartment 36. Liquid 34 returns to the reservoir via returnline or conduit 75. The reservoir contains an electric heater 76connected in circuit with thermostat 77 on return line which opens intothe bottom of compartment 36 via openings in frame 28 and frame 24 andpassage 79 in elastic frame 26; see FIG. 3. The thermostat has anadjustment knob 80.

FIG. 5 shows the circuitry of the system. Battery 102 is connected tokey operated ignition switch 104 conventionally provided in anautomotive vehicle. This switch is connected to an ignition coil (notshown). Connected to switch 104 is a manually operable master controlswitch 106 which selectively activates and deactivates the controlcircuitry of the windshield assembly. Connected in series with switch106 is a photoconductive photoelectric cell 108. This cell is connectedin series with adjustable resistor 1 10 and the coil of a relay 112. Therelay has normally closed contacts 114, which are open when the relay isenergized. This occurs when daylight impinges on the photoelectric cellto increase its conductance. Contact 115 is connected to switch 106.Contact 114 is connected in series with variable resistor 116 andsolenoid 65. The solenoid is energized only when contacts 114, l closeand this occurs only when the relay becomes deenergized due to decreasein the light level impinging on the photoelectric cell. When thesolenoid is energized it advances piston 64 to drive hydraulic fluidthrough conduits 60 and 58 to cylinders 47, 48. This advances pistons 54which then move the inner pane 24 forwardly to reduce the size ofcompartment 36.

A manually operable switch 118 is connected across contacts 114, 115 toshort circuit them when the contacts 114, 115 are open for operating thesolenoid 65 and moving pane 22 independently of the light intensityimpinging on the photoelectric cell.

The liquid 34 disposed between panes l8 and 24 is pumped via conduit 74by pump 70. The pump is driven by a motor 120. The pump draws liquid 34from reservoir 72 via pipe 73. Liquid is returned to the reservoir viaconduit 75. On this conduit is thermostat 77. The thermostat has amovable bimetallic element 122 disposed to contact adjustable terminal124 when the temperature of the returning liquid is below apredetermined value, for example 68 F. Element 122 is con nected inseries with the coil of relay 125. Terminal 124 is adjustably spacedfrom element 122 by means of adjustment knob 80. Terminal 124 isconnected to switch 106. Relay 125 has normally open contacts 126, 128connected in series with switch 106 and heater reservoir 72. When relay125 is energized due to fall in temperature of returning liquid 34,heater 76 becomes energized to heat the liquid. The heater 76 isconnected in parallel with motor 120 so that the motor runs and drivespump 70 to circulate the liquid 34 while it is being heated. A manuallyoperable switch 130 is connected in parallel with contacts 126, 128 torun the motor and heater at any time independently of the temperature ofthe liquid.

It will be apparent from the arrangement described, that the hydraulicsystem including master cylinder 62 and cylinders 47, 48 serve to reducethe volume of compartment 36 by moving the pane 24 forwardly toward pane18. The effect is to reduce the quantity of tinted liquid in chamber 36and thus increase its transparency. Therefore when ambient light fallingon the photoelectric cell decreases, the transparency of the windshieldis automatically increased. The light intensity value to which thephotoelectric cell will respond is adjusted by means of resistor 110.The distance that pane 24 moves is adjusted by variable resistor l 16.

FIG. 6 shows the various control switches and resistors mounted on acontrol panel 150 which can be installed adjacent to the dashboard ofthe vehicle. On panel 150 is master control switch 106, switch 118 whichenables manual operation of the hydraulic system to vary transparency ofthe windshield, and switch 130 which manually turns on the heater andpump. Adjustable control 80 sets the temperature at which the heater andpump will be operated. Adjustable resistor 110 sets the light intensityat which the photoelectric cell will respond and adjustable resistor 116sets the amount that the pane 24 will move. This occurs because themovement of pane 24 by the hydraulic system takes place againstcompressive resistance of elastic frame 26. Setting resistor 116 willdetermine then the force applied by the energized solenoid to thehydraulic system. Adjacent to panel is key operated ignition lockswitch104 which is connected in circuit with the system shown in FIG. 5.

An important feature of the invention is that the photoelectric cell orelectric eye operates the transparency controlling hydraulic systemautomatically. Thus the driver of the vehicle has his hands free tooperate the vehicle. Another important feature is that the heated liquidcirculates freely for defrosting the outer pane 18 and for evaporatingcondensed moisture on the innerpane 24. The circulation system is notrequired to mechanically separate the panes or reduce their spacing.This is done by the elasticity of frame 26 and the hydraulic system. Itwill be noted that the degree of tint is adjustable by adjustablyvarying the reduction in volume in chamber 36 by means of tint control116. Also the heated liquid can be circulated independently of spacingbetween panes 18, 24. This is an advantage over prior systems, wheretinted liquid was pumped into and out of the space between fixed andmovable panes to change their spacing. A further advantage of thepresent system is the automatic operation of the heater and liquidcirculation system to prevent frost and ice accumulation on thewindshield.

' The windshield assembly as described is simple to install and operate.It meets a long felt need in the automotive field for an improvedwindshield of variable transparency.

While a preferred embodiment of the invention has been described andillustrated, it will be apparent that many modifications are possiblewithout departing from the invention.

What is claimed is:

1. A windshield assembly comprising a first transparent window pane;first support means for mounting the same in an automotive vehicle foradmitting light into the vehicle; a second transparent window panedisposed parallel to and spaced from the first pane; elastic cushionmeans enclosing peripheries of both panes to define a compartmenttherebetween for containing a tinted liquid; second support means forthe second pane movably supporting the second pane to change its spacingfrom the first pane and to change thereby the volume of said compartmentand transparency of said liquid, mechanical means arranged to move thesecond pane toward the first pane against resistance of said elasticcushion means; liquid circulation means communicating with saidcompartment for circulating said liquid independently of the spacingbetween the panes; light responsive means disposed to sense ambientlight impinging on the window panes; and electromechanical meansoperatively arranged in connection with said mechanical means and saidlight responsive means to move the second pane toward the first panewhen the ambient light falls below a certain light intensity to increasethe transparency of liquid in said compartment; switch means connectedin circuit with the electromechanical means for moving said second paneto change the volume of said compartment independently of the intensityof ambient light impinging on the window panes; means for heating theliquid circulating through said compartment; switch means connected incircuit with the liquid circulation means for starting and stoppingcirculation of the liquid self-defrosting independently of thetemperature of the liquid sensed by the thermostat; said mechanicalmeans comprises hydraulic cylinders having pistons arranged to engageand move the second window pane, said electromechanical means beingarranged to drive hydraulic fluid into the cylinders for moving thesecond window pane; said liquid circulation means comprising a reservoirfor the liquid connected to said compartment, and a pump connectedbetween the reservoir and compartment to circulate the liquid throughthe compartment.

2. A windshield assembly as defined in claim 1, and electric controlmeans connected in circuit with the liquid circulation means andelectromechanical means for actuating the liquid circulation means andmechanical means independently of each other.

3. A windshield assembly as defined in claim 1, further comprising athermostat arranged to sense the temperature of said liquid circulatingthrough said compartment; and circuit means connecting the thermostat incircuit with the liquid circulation means to start and stop circulationof the liquid depending on the temperature setting of the thermostat.

4. A windshield assembly as defined in claim 1, further comprising otherswitch means connected in circuit with the electromechanical means formoving said second pane to change the volume of said compartmentindependently of the intensity of ambient light impinging on the windowpanes.

1. A windshield assembly comprising a first transparent window pane;first support means for mounting the same in an automotive vehicle foradmitting light into the vehicle; a second transparent window panedisposed parallel to and spaced from the first pane; elastic cushionmeans enclosing peripheries of both panes to define a compartmenttherebetween for containing a tinted liquid; second support means forthe second pane movably supporting the second pane to change its spacingfrom the first pane and to change thereby the volume of said compartmentand transparency of said liquid, mechanical means arranged to move thesecond pane toward the first pane against resistance of said elasticcushion means; liquid circulation means communicating with saidcompartment for circulating said liquid independently of the spacingbetween the panes; light responsive means disposed to sense ambientlight impinging on the window panes; and electromechanical meansoperatively arranged in connection with said mechanical means and saidlight responsive means to move the second pane toward the first panewhen the ambient light falls below a certain light intensity to increasethe transparency of liquid in said compartment; switch means connectedin circuit with the electromechanical means for moving said second paneto change the volume of said compartment independently of the intensityof ambient light impinging on the window panes; means for heating theliquid circulating through said compartment; switch means connected incircuit with the liquid circulation means for starting and stoppingcirculation of the liquid independently of the temperature of the liquidsensed by the thermostat; said mechanical means comprises hydrauliccylinders having pistons arranged to engage and move the second windowpane, said electromechanical means being arranged to drive hydraulicfluid into the cylinders for moving the second window pane; said liquidcirculation means comprising a reservoir for the liquid connected tosaid compartment, and a pump connected between the reservoir andcompartment to circulate the liquid through the compartment.
 2. Awindshield assembly as defined in claim 1, and electric control meansconnected in circuit with the liquid circulation means andelectromechanical means for actuating the liquid circulation means andmechanical means independently of each other.
 3. A windshield assemblyas defined in claim 1, further comprising a thermostat arranged to sensethe temperature of said liquid circulating through said compartment; andcircuit means connecting the thermostat in circuit with the liquidcirculation means to start and stop circulation of the liquid dependingon the temperature setting of the thermostat.
 4. A windshield assemblyas defined in claim 1, further comprising other switch means connectedin circuit with the electromechanical means for moving said second paneto change the volume of said compartment independently of the intensityof ambient light impinging on the window panes.